This invention relates to a Group 4 metal complex, to a catalyst composition and to a process for polymerizing addition polymerizable unsaturated monomers, especially olefins. In particular, the invention is directed to certain Group 4 metal complexes, to catalyst compositions comprising the same, and to addition polymerization processes using the same.
Advances in polymerization and catalysis have resulted in the capability to produce many new polymers having improved physical and chemical properties useful in a wide variety of superior products and applications. With the development of new catalysts the choice of polymerization-type (solution, slurry, high pressure or gas phase) for producing a particular polymer has been greatly expanded. Also, advances in polymerization technology have provided more efficient, highly productive and economically enhanced processes. Recently, several new disclosures related to metal complexes based on donor ligands have published. Among these are U.S. Pat. No. 6,103,657, US2002 0142912, WO 2000 020377 and WO 2002 038628. Regardless of these technological advances in the polyolefin industry, common problems, as well as new challenges associated with process operability, still exist. For example, the tendency for known Group 4 metal complexes to lose catalyst operating efficiency at high polymerization temperatures in solution polymerization processes remains a challenge. Additionally, improved solubility of the metal complex in common aliphatic solvents is desired.
In particular, in a continuous solution polymerization process, operation at high polymerization temperatures, especially temperatures greater than 100° C., more preferably greater than 110° C., are desired in order to increase the operating efficiency of the process. In addition, by operating at elevated polymerization temperatures, olefin polymers having unique physical properties, composition, and structure may be prepared.
Thus, it would be advantageous to have a polymerization process capable of operating continuously with enhanced reactor efficiency and at the same time produce new and improved polymers. It would also be highly beneficial to have a continuously operating solution polymerization process having more stable catalyst productivity, improved efficiency, and increased duration of operation.